U.S. patent application number 12/865011 was filed with the patent office on 2010-12-23 for magnetic circuit and audio equipment.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. Invention is credited to Masahiko Miyazaki, Shinji Murakami.
Application Number | 20100322460 12/865011 |
Document ID | / |
Family ID | 40912595 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100322460 |
Kind Code |
A1 |
Miyazaki; Masahiko ; et
al. |
December 23, 2010 |
MAGNETIC CIRCUIT AND AUDIO EQUIPMENT
Abstract
[Problem] To provide a magnetic circuit whose size and thickness
can be reduced, and which can generate a high sound pressure by a
simple structure. [Means for Resolution] A magnetic circuit of the
present invention includes a horizontal coil wound in a horizontal
direction, and an unitary magnet opposed face-to-face to the
horizontal coil, wherein the magnet has a first polarity portion
and a second polarity portion located adjacent to the first
polarity portion. The first polarity portion and the second
polarity portion are magnetized mutually in an opposite direction
in a direction of a center axis of the horizontal coil, and the
second polarity portion is arranged between one area of the first
polarity portion and other area of the first polarity portion in a
horizontal plane of the magnet.
Inventors: |
Miyazaki; Masahiko; (Osaka,
JP) ; Murakami; Shinji; (Hyogo, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
SANYO ELECTRIC CO., LTD.
Moriguchi-shi, Osaka
JP
|
Family ID: |
40912595 |
Appl. No.: |
12/865011 |
Filed: |
January 16, 2009 |
PCT Filed: |
January 16, 2009 |
PCT NO: |
PCT/JP2009/050572 |
371 Date: |
July 28, 2010 |
Current U.S.
Class: |
381/412 ;
335/209 |
Current CPC
Class: |
H04R 9/025 20130101 |
Class at
Publication: |
381/412 ;
335/209 |
International
Class: |
H04R 11/02 20060101
H04R011/02; H01F 7/20 20060101 H01F007/20; H01F 7/02 20060101
H01F007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2008 |
JP |
2008-016511 |
Claims
1. A magnetic circuit, comprising: a horizontal coil wound in a
horizontal direction; and an unitary magnet that is opposed
face-to-face to the horizontal coil; wherein the magnet has a first
polarity portion and a second polarity portion that is located
adjacent to the first polarity portion, the first polarity portion
and the second polarity portion are magnetized mutually in an
opposite direction in a direction of a center axis of the
horizontal coil, and the second polarity portion is arranged
between one area of the first polarity portion and other area of
the first polarity portion in a horizontal plane of the magnet.
2. The magnetic circuit according to claim 1, wherein the second
polarity portion is surrounded by the first polarity portion in the
horizontal plane of the magnet.
3. The magnetic circuit according to claim 1, wherein the second
polarity portion is put between a plurality of first polarity
portions in the horizontal plane of the magnet.
4. The magnetic circuit according to claim 1, wherein at least a
part of horizontal coil is arranged on a boundary between the first
polarity portion and the second polarity portion of the magnet.
5. The magnetic circuit according to claim 1, wherein the
horizontal coil is arranged such that at least a part of a center
portion between an outer periphery and an inner periphery of the
horizontal coil is positioned on the boundary between the first
polarity portion and the second polarity portion of the magnet.
6. The magnetic circuit according to claim 1, wherein the magnet
has a ferromagnetic plate on both surfaces or one surface of the
horizontal plane.
7. An audio equipment comprising: a magnetic circuit; and a
diaphragm; the magnetic circuit has a horizontal coil that is wound
in a horizontal direction, and an unitary magnet face-to-face
opposed to the horizontal coil, the magnet has a first polarity
portion and a second polarity portion located adjacent to the first
polarity portion, the first polarity portion and the second
polarity portion are magnetized mutually in an opposite direction
in a direction of a center axis of the horizontal coil, and the
second polarity portion is arranged between one area of the first
polarity portion and other area of the first polarity portion in a
horizontal plane of the magnet, and the horizontal coil or the
magnet are fixed to the diaphragm, and the diaphragm is vibrated by
acting magnetic fluxes of the magnet on the horizontal coil to
apply an electric current to the horizontal coil.
Description
TECHNICAL FIELD
[0001] The present invention relates to a magnetic circuit capable
of showing a high sound pressure performance by a small and slim
structure. Also, the present invention relates to an
audio-equipment that is equipped with such magnetic circuit and is
easy to manufacture at a low cost.
BACKGROUND ART
[0002] A reduction in size and thickness of a personal digital
assistant such as a cellular phone advances rapidly, and also needs
for a reduction in size and thickness are enhanced in an audio
equipment such as a speaker employed in the personal digital
assistant. A sectional view of a slim speaker in the background art
is illustrated in FIG. 5 (see Patent Literature 1). As shown in
FIG. 5, this slim speaker has a diaphragm 52, a magnet 53, and a
horizontal coil 54 in the inside of a frame 50 in which sound
emitting holes 51 are opened. An outer peripheral portion of the
diaphragm 52 is secured to the frame 50. The horizontal coil 54 is
arranged in a center portion of the diaphragm 52, and a center axis
T of the horizontal coil 54 is aligned perpendicularly to the
diaphragm 52. The circular disk type magnet 53 is arranged
coaxially with the center axis T of the horizontal coil 54, and is
magnetized in the direction parallel to the center axis T. An air
gap G is provided between the circular disk type magnet 53 and the
horizontal coil 54.
[0003] In the slim speaker in shown in FIG. 5, magnetic fluxes M
(each indicated with a broken line arrow) are radiated form the
magnet 53, and the magnetic fluxes M act on the coil 54 through the
air gap G. Thus, when an electric current supplied to the coil 54
is changed, the diaphragm 52 is driven to vibrate. Since the coil
54 is has a flat shape in which the number of laminations in the
horizontal direction that intersects orthogonally with the center
axis T is larger than the number of laminations in the direction of
the center axis T, the slimming down can be achieved in the speaker
shown in FIG. 5. However, since this speaker employs a single
magnet that is magnetized in one direction, such a problem exists
that the sound pressure performance is lowered according to the
reduction in size and thickness.
[0004] A sectional view of a slim speaker in the prior art in
another mode is illustrated in FIG. 6. As shown in FIG. 6, this
slim speaker has a diaphragm 62, a magnet 63, and a horizontal coil
64 in the inside of a frame 60. An outer peripheral portion of the
diaphragm 52 is put between the frame 60 and a cover 65, and is
secured thereto. The horizontal coil 64 is secured to the back
surface of the diaphragm 62, the horizontal coil 64 is wound flatly
along the center axis T, and the center axis T is aligned
perpendicularly to the diaphragm 62. The magnet 63 is arranged to
face-to-face oppose to the horizontal coil 64, and is magnetized in
the direction parallel to the center axis T. The magnet 63 is
composed of a pair of outer magnets 63a each shaped into a
rectangular parallelepiped, and an inner magnet 63b shaped into a
rectangular parallelepiped. Since the horizontal coil 64 is wound
flatly, and a reduction in size and thickness of the speaker can be
achieved.
[0005] Perspective views of a magnet employed in the slim speaker
in the prior art are shown in FIG. 7. As shown in FIG. 7 (a), the
magnet 63 is composed of a pair of outer magnets 63a, and the inner
magnet 63b. The outer magnets 63a and the inner magnet 63b are
magnetized in the opposite direction. A state of a magnetic flux
that is formed by the magnet is shown in FIG. 8. As shown in FIG.
8(a), the magnetic fluxes formed by the inner magnet 63b and the
magnetic fluxes formed by the outer magnets 63a are superposed
mutually, so that the magnetic fluxes with high density pass
through the coil 64. As a result, a driving force acting on the
diaphragm is increased, and a sound pressure can be enhanced.
[0006] When such a structure shown in FIG. 7(b) is employed that
the surface of the inner magnet 63b is protruded toward the coil
side from the surfaces of the outer magnets 63a, the magnetic
fluxes shown in FIG. 8 (b) are formed. Thus, the magnetic fluxes of
higher density can be acted on the coil 64. However, a magnetic
circuit structure that needs an arrangement of a plurality of
magnets is high in material cost, and the productivity of the
magnetic circuit is lowered. Also, when such a structure is
employed that the surface of the inner magnet is protruded toward
the coil side from the surfaces of the outer magnets, a shape of
the magnet becomes complicated, and the handling of the magnet is
required.
[0007] Patent Literature 1: Japanese Patent No. 3213521
DISCLOSURE OF THE INVENTION
Problems that the Invention is to Solve
[0008] It is an object of the present invention to provide a
magnetic circuit whose size and thickness can be reduced, and which
can generate a high sound pressure by a simple structure. Also, it
is another object of the present invention to provide an audio
equipment that shows a high sound pressure performance by a small
and slim structure, and is easy to manufacture at a low cost.
Means for Solving the Problems
[0009] A magnetic circuit of the present invention comprises a
horizontal coil wound in a horizontal direction; and an unitary
magnet opposed face-to-face to the horizontal coil; wherein the
magnet has a first polarity portion and a second polarity portion
located adjacent to the first polarity portion. The first polarity
portion and the second polarity portion are magnetized mutually in
an opposite direction in a direction of a center axis of the
horizontal coil, and the second polarity portion is arranged
between one area of the first polarity portion and other area of
the first polarity portion in a horizontal plane of the magnet.
Such a mode is preferable that the second polarity portion is
surrounded with the first polarity portion in the horizontal plane
of the magnet, or such a mode is preferable that the second
polarity portion is put between a plurality of first polarity
portions in the horizontal plane of the magnet.
[0010] Such a mode is preferable that at least a part of horizontal
coil should be arranged on the boundary between the first polarity
portion and the second polarity portion of the magnet. In
particular, such a mode is more preferable that at least a part of
center portion between an outer periphery and an inner periphery of
the horizontal coil should be arranged on the boundary between the
first polarity portion and the second polarity portion of the
magnet. Also, such a mode is preferable that the magnet should have
the ferromagnetic plate on both surfaces or a single surface of the
horizontal plane.
[0011] An audio equipment of the present invention includes a
magnetic circuit; and a diaphragm; the magnetic circuit has a
horizontal coil that is wound in a horizontal direction, and a
single magnet face-to-face opposed to the horizontal coil. The
magnet has a first polarity portion and a second polarity portion
located adjacent to the first polarity portion, the first polarity
portion and the second polarity portion are magnetized mutually in
an opposite direction in a direction of a center axis of the
horizontal coil, and the second polarity portion is arranged
between one area of the first polarity portion and other area of
the first polarity portion in a horizontal plane of the magnet. The
horizontal coil or the magnet are fixed to the diaphragm, and the
diaphragm is vibrated by acting magnetic fluxes of the magnet on
the horizontal coil to apply an electric current to the horizontal
coil.
ADVANTAGE OF THE INVENTION
[0012] The magnetic circuit whose structure is simply, which is
small in size and slim in thickness, and whose sound pressure
performance is high can be provided.
BEST MODE FOR CARRYING OUT THE INVENTION
Magnetic Circuit
First Embodiment
[0013] A structure of a magnetic circuit according to a first
embodiment of the present invention is shown in FIG. 1. FIG. 1 (a)
is a plan view and a sectional view taken along IB-IB is FIG. 1
(b). FIG. 1(c) is a view showing schematically the magnetic fluxes
formed by a magnet. As shown in FIG. 1 (a), this magnetic circuit
consists of a horizontal coil 4 and a magnet 3. As shown in FIG. 1
(b), the horizontal coil 4 is face-to-face opposed to the magnet 3,
and the magnet 3 is composed of an unitary plate member. In the
present embodiment, the plate-like magnet 3 is employed. But the
magnet 3 in the present invention is not limited to the plate
member, and it is effective to employ a cubic magnet, a rectangular
parallelepiped magnet, or the like, for example. This is true of
other embodiments. The magnet 3 has a first polarity portion 3a and
a second polarity portion 3b located adjacent to the first polarity
portion 3a. As shown in FIG. 1 (a), the second polarity portion 3b
is arranged between one area A1 of the first polarity portion 3a
and other area A2 of the first polarity portion 3a in the
horizontal plane of the magnet 3. In an example shown in FIG. 1, as
shown in FIG. 1 (a), the magnet 3 has such a structure that the
second polarity portion 3b is surrounded with the first polarity
portion 3a in the horizontal plane of the magnet 3. Also, the first
polarity portion 3a and the second polarity portion 3b are
magnetized in the opposite direction in the direction of the center
axis of the horizontal coil 4. In the example shown in FIG. 1, the
first polarity portion 3a is magnetized such that the upper surface
becomes the S-pole in the direction of the center axis of the
horizontal coil 4, and the second polarity portion 3b is magnetized
such that the upper surface becomes the N-pole in the direction of
the center axis of the horizontal coil 4. The similar advantage can
be achieved even when the N-pole and the S--pole are magnetized
oppositely.
[0014] Since the first polarity portion 3a is magnetized in the
direction of the center axis of the horizontal coil 4, magnetic
fluxes Y11, Y12 are formed by the first polarity portion 3a, as
shown in FIG. 1(c). The second polarity portion 3b is arranged
adjacent to the first polarity portion 3a, and the second polarity
portion 3b is arranged between the first polarity portions 3a.
Also, since the second polarity portion 3b is magnetized in the
direction of the center axis of the horizontal coil 4 and the
direction of its magnetization is opposite to the first polarity
portion 3a, magnetic fluxes Z1 are formed by the second polarity
portion 3b, as shown in FIG. 1(c). As a result, as shown in FIG.
1(c), the magnetic fluxes Y12 formed by the first polarity portions
3a and the magnetic fluxes Z1 formed by the second polarity portion
3b are superposed mutually in the horizontal coil 4, and thus a
magnetic flux density acting on the horizontal coil 4 in the
horizontal direction is increased, so that a sound pressure
performance can be enhanced.
[0015] The magnetic circuit in the present embodiment is
constructed by a single magnet. Therefore, a structure of this
magnetic circuit is simple rather than the conventional magnetic
circuit constructed by a plurality of magnets, a material cost can
be reduced, and the productivity can be enhanced. Also, the first
polarity portion and the second polarity portion that are
magnetized in the opposite direction mutually are provided to the
unitary magnet. Therefore, a sound pressure performance can be
enhanced rather than the conventional magnetic circuit constructed
by a unitary magnet that is magnetized on one direction. Further,
the magnetic circuit is constructed by the flat horizontal coil
that is wound in the horizontal direction, and the magnet.
Therefore, the small and slim magnetic circuit can be provided.
[0016] In the example shown in FIG. 1 (a), the horizontal coil 4 is
wound concentrically in the horizontal direction, but the
horizontal coil is not limited to the circular shape. The
horizontal coil that is wounded in a polygonal shape such as a
quadrangular shape, a hexagonal shape, or the like can be employed
effectively to fit in with shapes of the first polarity portion and
the second polarity portion in the magnet or meet the requested
needs. In FIG. 12, a planar shape of the horizontal coil is shown.
FIG. 12 (a) shows an example of the horizontal coil that is wound
like a circle, similarly to FIG. 1 (a). FIG. 12 (b) to FIG. 12 (e)
show an example of the horizontal coil that is wound longer in one
direction respectively, wherein FIG. 12 (b) shows a quadrangular
shape, FIG. 12 (c) shows an elliptic shape, FIG. 12 (d) shows a
track shape, and FIG. 12 (e) shows a hexagonal shape. In the
present specification, the center axis of the horizontal coil
denotes an axis that passes through a center of gravity C of the
horizontal coil in a horizontal plane and intersects orthogonally
with the horizontal plane.
Second Embodiment
[0017] A structure of a magnetic circuit according to a second
embodiment of the present invention is shown in FIG. 2. FIG. 2 (a)
is a plan view and a sectional view taken along IIB-IIB is FIG. 2
(b). FIG. 2 (c) is a view showing schematically the magnetic fluxes
formed by the magnet. As shown in FIG. 2 (a), this magnetic circuit
is composed of the horizontal coil 4 and the magnet 3. As shown in
FIG. 2 (b), the horizontal coil 4 is face-to-face opposed to the
magnet 3, and the magnet 3 is formed of a unitary plate member. The
magnet 3 has the first polarity portion 3a and the second polarity
portion 3b located adjacent to the first polarity portion 3a. As
shown in FIG. 2 (a), the second polarity portion 3b is arranged
between one area A1 of the first polarity portion 3a and other area
A2 of the first polarity portion 3a in the horizontal plane of the
magnet 3. In an example shown in FIG. 2, as shown in FIG. 2 (a),
the magnet 3 has such a structure that the second polarity portion
3b is surrounded with the first polarity portion 3a in the
horizontal plate of the magnet 3. Also, the first polarity portion
3a and the second polarity portion 3b are magnetized in the
opposite direction in the direction of the center axis of the
horizontal coil 4. Also, the magnet 3 has a ferromagnetic plate 5
as a plate member made of ferromagnetic material such as iron,
Permalloy, or the like on the bottom surface of the horizontal
plane.
[0018] Therefore, as shown in FIG. 2 (c), magnetic fluxes Y21, Y21
that the first polarity portion 3a emits and magnetic fluxes Z2
that the second polarity portion 3b emits are caused to pass
through the ferromagnetic plate 5. Accordingly, since the magnetic
fluxes are attracted toward the horizontal coil 4, the magnetic
flux density acting on the horizontal coil 4 in the horizontal
direction is enhanced and thus the sound pressure performance can
be enhanced. Also, since the ferromagnetic plate 5 is formed on the
bottom surface of the magnet 3, demagnetization of the magnet 3 can
be suppressed. The magnetic flux densities of the magnetic fluxes
Y22 that the first polarity portion 3a emits and the magnetic
fluxes Z2 that the second polarity portion 3b emits in the
horizontal direction become maximum on the boundary between the
first polarity portion 3a and the second polarity portion 3b.
Therefore, from a viewpoint that a sound pressure performance
should be enhanced by increasing the magnetic flux density acting
on the horizontal coil 4 in the horizontal direction, such a mode
is preferable that at least a part of horizontal coil 4 should be
arranged on the boundary between the first polarity portion 3a and
the second polarity portion 3b of the magnet 3. In particular, from
a viewpoint that the magnetic flux density in the horizontal
direction should become maximum in a center portion 4c in the
winding existing area of the horizontal coil 4 that is wound in the
horizontal direction, such a mode is preferable that at least a
part of center portion 4c between an outer periphery 4a and an
inner periphery 4b of the horizontal coil 4 should be arranged on
the boundary between the first polarity portion 3a and the second
polarity portion 3b of the magnet 3.
[0019] In the present embodiment, like the first embodiment, the
magnetic fluxes Y22 formed by the first polarity portion 3a and the
magnetic fluxes Z2 formed by the second polarity portion 3b are
superposed mutually in the horizontal coil 4, and the magnetic flux
density acting on the horizontal coil 4 in the horizontal direction
is increased. Therefore, the sound pressure performance can be
enhanced. Also, the magnetic circuit is constructed by a unitary
magnet. Therefore, a structure of this magnetic circuit is simple,
a material cost can be reduced, and the productivity can be
enhanced. Also, the sound pressure performance is increased rather
than the conventional magnetic circuit that is constructed by a
unitary magnet that is magnetized in one direction. Also, the
magnetic circuit is constructed by the flat horizontal coil that is
wound in the horizontal direction, and the magnet. Therefore, the
small and slim magnetic circuit can be provided.
Third Embodiment
[0020] A structure of a magnetic circuit according to a third
embodiment of the present invention is shown in FIG. 3. FIG. 3 (a)
is a plan view and a sectional view taken along IIIB-IIIB is FIG. 3
(b). FIG. 3(c) is a view showing schematically the magnetic fluxes
formed by the magnet. As shown in FIG. 3 (a), this magnetic circuit
is constructed by the horizontal coil 4, and the magnet 3. As shown
in FIG. 3 (b), the horizontal coil 4 is face-to-face opposed to the
magnet 3, and the magnet 3 is a unitary plate member. The magnet 3
has the first polarity portion 3a and the second polarity portion
3b located adjacent to the first polarity portion 3a. As shown in
FIG. 3 (a), the second polarity portion 3b is arranged between one
area A1 of the first polarity portion 3a and other area A2 of the
first polarity portion 3a in the horizontal plane of the magnet 3.
In an example shown in FIG. 3, as shown in FIG. 3(a), the magnet 3
has such a structure that the second polarity portion 3b is
surrounded with the first polarity portion 3a in the horizontal
plate of the magnet 3. In the example shown in FIG. 3, from a
viewpoint that a structure of a magnetized yoke can be made simple,
it is preferable that such a mode should be employed that the
magnetic circuit is magnetized linearly. The first polarity portion
3a and the second polarity portion 3b are magnetized in the
opposite direction mutually in the direction of the center axis of
the horizontal coil 4. Also, the magnet 3 has the ferromagnetic
plate 5 made of iron, Permalloy, or the like on the bottom.
[0021] The magnetic flux densities of magnetic fluxes Y32 that the
first polarity portion 3a emits and magnetic flux Z3 that the
second polarity portion 3b emits in the horizontal direction become
maximum on the boundary between the first polarity portion 3a and
the second polarity portion 3b. Therefore, from a viewpoint that
the sound pressure performance should be enhanced by increasing the
magnetic flux density acting on the horizontal coil 4 in the
horizontal direction, such a mode is preferable that at least a
part of horizontal coil 4 should be arranged on the boundary
between the first polarity portion 3a and the second polarity
portion 3b of the magnet. In particular, from a viewpoint that the
magnetic flux density in the horizontal direction become maximum in
the center portion 4c of the winding existing area of the
horizontal coil 4 that is wound in the horizontal direction, such a
mode is preferable that at least a part of center portion 4c
between the outer periphery 4a and the inner periphery 4b of the
horizontal coil 4 should be arranged on the boundary between the
first polarity portion 3a and the second polarity portion 3b of the
magnet 3.
[0022] In the present embodiment, like the first embodiment, the
magnetic fluxes formed by the first polarity portion 3a and the
magnetic fluxes formed by the second polarity portion 3b are
superposed mutually in the horizontal coil 4. Therefore, the sound
pressure performance can be enhanced. Also, the magnetic circuit is
constructed by a unitary magnet. Therefore, the structure is made
simple, a material cost can be reduced, and the productivity can be
enhanced. Also, the sound pressure performance can be improved
rather than the conventional magnetic circuit constructed by a
unitary magnet that is magnetized in one direction. Also, the
magnetic circuit is constructed by the flat horizontal coil that is
wound in the horizontal direction, and the magnet. Therefore, the
small and slim magnetic circuit can be provided. Also, like the
second embodiment, the sound pressure performance can be enhanced
by providing the ferroelectric plate on the bottom surface of the
magnet, and demagnetization of the magnet can be suppressed.
Fourth Embodiment
[0023] A structure of a magnetic circuit according to a fourth
embodiment of the present invention is shown in FIG. 4. FIG. 4 (a)
is a plan view and a sectional view taken along IVB-IVB is FIG. 4
(b). FIG. 4 (c) is a view showing schematically the magnetic fluxes
formed by the magnet. As shown in FIG. 4 (a), this magnetic circuit
is composed of the horizontal coil 4 and the magnet 3. As shown in
FIG. 4 (b), the horizontal coil 4 is face-to-face opposed to the
magnet 3, and the magnet 3 is formed of a unitary plate member. The
magnet 3 has the first polarity portion 3a, and the second polarity
portion 3b located adjacent to the first polarity portion 3a. As
shown in FIG. 4 (a), the second polarity portion 3b is arranged
between one area A1 of the first polarity portion 3a and other area
A2 the first polarity portion 3a in the horizontal plate of the
magnet 3. The first polarity portion 3a and the second polarity
portion 3b are magnetized mutually in the opposite direction in the
direction of the center axis of the horizontal coil 4. Also, the
magnet 3 has the ferromagnetic plate 5 on the bottom surface in the
horizontal plane, and has a ferromagnetic plate 6 on the upper
surface.
[0024] When the ferromagnetic plate 6 made of iron, Permalloy, or
the like is formed on the upper surface of the magnet 3, the
magnetic fluxes passing through the ferromagnetic plate 6 are
formed as shown in FIG. 4(c), and the ferromagnetic plate 6
attracts magnetic fluxes Y42, Z4. Therefore, the magnetic flux
density acting on the horizontal coil 4 in the horizontal direction
is increased, and the sound pressure performance can be enhanced.
In the present embodiment, like the first embodiment, the magnetic
fluxes formed by the first polarity portion 3a and the second
polarity portion 3b are superposed mutually in the horizontal coil
4. Therefore, the sound pressure performance becomes high. Also,
the magnetic circuit is constructed by a unitary magnet. Therefore,
a structure is simple, and the sound pressure performance can be
improved rather than the conventional magnetic circuit made of a
unitary magnet that is magnetized in one direction. Also, since the
magnetic circuit is constructed by the flat horizontal coil and the
magnet, the small and slim magnetic circuit can be provided. Also,
since the magnetic circuit has the ferromagnetic plate on the
bottom surface of the magnet, demagnetization of the magnet can be
suppressed.
Fifth Embodiment
[0025] A structure of a magnetic circuit according to a fifth
embodiment of the present invention is shown in FIG. 9. FIG. 9 (a)
is a plan view, and a sectional view taken along IXB-IXB is FIG. 9
(b), FIG. 9(c) is a view showing schematically the magnetic fluxes
formed by the magnet. As shown in FIG. 9 (a), this magnetic circuit
is constructed by the horizontal coil 4 and the magnet 3. As shown
in FIG. 9 (b), the horizontal coil 4 is face-to-face opposed to the
magnet 3, and the magnet 3 is formed of a unitary plate member. The
magnet 3 has the first polarity portion 3a, and the second polarity
portion 3b located adjacent to the first polarity portion 3a. As
shown in FIG. 9 (a), the second polarity portion 3b is arranged
between one area A1 of the first polarity portion 3a and other area
A2 of the first polarity portion 3a in the horizontal plane of the
magnet 3. The first polarity portion 3a and the second polarity
portion 3b are magnetized mutually in the opposite direction in the
direction of the center axis of the horizontal coil 4. Also, the
magnet 3 has the ferromagnetic plate 5 on the bottom surface, and
also a ferromagnetic plate 7 on the upper surface.
[0026] When the ferromagnetic plate 7 made of iron, Permalloy, or
the like is formed on the upper surface of the magnet 3, magnetic
fluxes Z9, Y91 passing through the ferromagnetic plate 7 is formed,
as shown in FIG. 9 (c), and the ferromagnetic plate 7 attracts
magnetic fluxes Y92, Z9. Therefore, the magnetic flux density
acting on the horizontal coil 4 in the horizontal direction is
increased, and the sound pressure performance can be enhanced. In
the present embodiment, like the first embodiment, the magnetic
fluxes formed by the first polarity portion 3a and the second
polarity portion 3b are superposed mutually in the horizontal coil
4. Therefore, the sound pressure performance becomes high. Also,
the magnetic circuit is constructed by a unitary magnet. Therefore,
the structure is simple, and the sound pressure performance is
improved rather than the conventional magnetic circuit formed of a
unitary magnet that is magnetized in one direction. Also, since the
magnetic circuit is constructed by the flat horizontal coil and the
magnet, a reduction in size and thickness can be easily attained,
Like the second embodiment, since the ferromagnetic plate is
provided on the bottom surface of the magnet, the sound pressure
performance becomes high and demagnetization of the magnet can be
suppressed.
Sixth Embodiment
[0027] A structure of a magnetic circuit according to a sixth
embodiment of the present invention is shown in FIG. 10. FIG. 10
(a) is a plan view and a sectional view taken along XB-XB is FIG.
10 (b). FIG. 10 (c) is a view showing schematically the magnetic
fluxes formed by the magnet. As shown in FIG. 10 (a), this magnetic
circuit is constructed by the horizontal coil 4 and the magnet 3.
As shown in FIG. 10 (b), the horizontal coil 4 is face-to-face
opposed to the magnet 3, and the magnet 3 is a unitary plate
member. The magnet 3 has the first polarity portion 3a and the
second polarity portion 3b located adjacent to the first polarity
portion 3a. As shown in FIG. 10 (a), the second polarity portion 3b
is arranged between one area A1 of the first polarity portion 3a
and other area A2 of the first polarity portion 3a in the
horizontal plane of the magnet 3. The first polarity portion 3a and
the second polarity portion 3b are magnetized mutually in the
opposite direction in the direction of the center axis of the
horizontal coil 4. Also, the magnet 3 has the ferromagnetic plate 5
on the bottom surface, and has further the ferromagnetic plates 6,
7 on the upper surface.
[0028] Like the fourth embodiment and the fifth embodiment, when
the ferromagnetic plates 6, 7 made of iron, Permalloy, or the like
are formed on the upper surface of the magnet 3, magnetic fluxes
Z10 passing through the ferromagnetic plates 6, 7 are formed, as
shown in FIG. 10(c), and the ferromagnetic plates 6, 7 attract the
magnetic fluxes respectively. Therefore, the magnetic flux density
acting on the horizontal coil 4 in the horizontal direction is
increased, and the sound pressure performance can be enhanced.
Also, like the second embodiment, the ferromagnetic plate 5 is
provided on the bottom surface of the magnet. Therefore, the sound
pressure performance becomes high, and demagnetization of the
magnet can be suppressed. In the present embodiment, like the first
embodiment, the magnetic fluxes formed by the first polarity
portion 3a and the second polarity portion 3b are superposed
mutually in the horizontal coil 4. Therefore, the sound pressure
performance can be improved. Also, the magnetic circuit is
constructed by a unitary magnet. Therefore, the structure becomes
simple, and the sound pressure performance can be enhanced rather
than the conventional magnetic circuit made of a unitary magnet
that is magnetized in one direction. Also, the sound pressure
performance is constructed by the flat horizontal coil and the
magnet. Therefore, the small and slim magnetic circuit can be
provided.
Seventh Embodiment
[0029] A structure of a magnetic circuit according to a seventh
embodiment of the present invention is shown in FIG. 11. FIG. 11
(a) is a plan view and a sectional view taken along XIB-XIB is FIG.
11 (b). FIG. 11(c) is a view showing schematically the magnetic
fluxes formed by the magnet. As shown in FIG. 11 (a), this magnetic
circuit is constructed by the horizontal coil 4 and the magnet 3.
As shown in FIG. 11 (b), the horizontal coil 4 is face-to-face
opposed to the magnet 3, and the magnet 3 is formed of a unitary
plate member. The magnet 3 has the first polarity portion 3a and
the second polarity portion 3b located adjacent to the first
polarity portion 3a. As shown in FIG. 11 (a), the second polarity
portion 3b is arranged between one area A1 of the first polarity
portion 3a and other area A2 of the first polarity portion 3a in
the horizontal plane of the magnet 3. The first polarity portion 3a
and the second polarity portion 3b are magnetized in the opposite
direction in the direction of the center axis of the horizontal
coil 4. Also, the magnet 3 has the ferromagnetic plate 5 made of
iron, Permalloy, or the like on the bottom surface.
[0030] As shown in FIG. 11(a), this magnetic circuit has such a
structure that two second polarity portions 3b are surrounded with
one first polarity portion 3a in the horizontal plane of the magnet
3. Therefore, the layout of the magnetic circuit is made compact
intensively, and miniaturization of the magnetic circuit can be
facilitated much more. Also, like the second embodiment, this
magnetic circuit has the ferromagnetic plate on the bottom surface
of the magnet. Therefore, the sound pressure performance can be
improved, and demagnetization of the magnet can be suppressed. In
the present embodiment, like the first embodiment, the magnetic
fluxes formed by the first polarity portion 3a and the second
polarity portion 3b are superposed mutually in the horizontal coil
4. Therefore, the sound pressure performance becomes high. Also,
the magnetic circuit is constructed by a unitary magnet. Therefore,
the structure is made simple, and the sound pressure performance is
increased rather than the conventional magnetic circuit formed of a
unitary magnet that is magnetized on one direction. Also, the
magnetic circuit is constructed by the flat horizontal coil and the
magnet. Therefore, a reduction in size and thickness is
facilitated.
Audio Equipment
Eighth Embodiment
[0031] A structure of an audio-equipment according to an eighth
embodiment of the present invention is shown in FIG. 13. FIG. 13
(a) and FIG. 13 (a) are perspective views, and a sectional view
taken along XIIIC-XIIIC in FIG. 13 (a) is FIG. 13 (c). As
illustrated in FIG. 13 (a), this audio equipment has a flat
cylindrical frame 8, and a circular-disc cover 10 provided in the
opening portion in the front surface of the frame 8. This cover 10
has a plurality of sound emitting holes 9. A circular magnetic
circuit as shown in FIG. 1 (a), for example, is installed into the
audio equipment shown in FIG. 13 (a). As shown in FIG. 13 (c), the
interior of the frame 8 is constructed by the magnetic circuit and
a diaphragm 11, and an outer peripheral portion of the diaphragm 11
is fixed to the frame 8. The magnetic circuit is constructed by the
horizontal coil 4, and the magnet 3. The horizontal coil 4 is
face-to-face opposed to the magnet 3, and the magnet 3 is formed of
a unitary plate member. The magnet 3 has the first polarity portion
3a, and the second polarity portion 3b located adjacent to the
first polarity portion 3a. The second polarity portion 3b is
arranged between one area of the first polarity portion 3a and
other area of the first polarity portion 3a in the horizontal plane
of the magnet 3. For example, as shown in FIG. 1 (a) or FIG. 2 (a),
the magnetic circuit can be constructed such that the second
polarity portion 3b is surrounded with the first polarity portion
3a in the horizontal plane of the magnet 3. On the contrary, as
shown in FIG. 3 (a), the magnetic circuit can be constructed such
that the second polarity portion 3b is surrounded with a plurality
of first polarity portions 3a in the horizontal plane of the magnet
3.
[0032] The first polarity portion 3a and the second polarity
portion 3b are magnetized in the opposite direction in the
direction of the center axis of the horizontal coil 4. In FIG. 13
(c), such a mode is illustrated that the horizontal coil 4 and the
diaphragm 11 are fixed mutually. But such a mode may be employed
that arrangement of the horizontal coil 4 and the magnet 3 is
changed, and the magnet 3 is fixed the diaphragm 11, in place of
the horizontal coil 4. Such a mode is preferable that at least a
part of horizontal coil 4 should be arranged on the boundary
between the first polarity portion 3a and the second polarity
portion 3b of the magnet 3. Such a mode is more preferable that at
least a part of center portion between the outer periphery and the
inner periphery of the horizontal coil 4 should be arranged on the
boundary between the first polarity portion 3a and the second
polarity portion 3b of the magnet 3. Also, such a mode is
preferable that the magnet 3 should have the ferromagnetic plate on
both surfaces or a single surface of the horizontal plane.
[0033] This audio equipment can be used effectively as a speaker or
a receiver, for example, by driving the diaphragm when the magnetic
fluxes of the magnet are caused to act on the horizontal coil 4 by
applying an electric current to the horizontal coil 4. The audio
equipment shown in FIG. 13 (b) is equipped with the flat
cylindrical frame 8 having a long, narrow or elliptic planar shape,
and the long, narrow or elliptic cover 10 provided in the opening
portion in the front surface of the frame 8. This cover 10 has a
plurality of sound emitting holes 9. The long, narrow or elliptic
magnetic circuit shown in FIG. 11 (a), for example, can be
installed into such audio equipment. Like the first embodiment, the
magnetic fluxes formed by the first polarity portion 3a and the
second polarity portion 3b are superposed mutually in the
horizontal coil 4. Therefore, the sound pressure performance
becomes high. Also, the magnetic circuit is constructed by a
unitary magnet. Therefore, the structure is simple, and the sound
pressure performance is increased rather than the conventional
magnetic circuit constructed by a unitary magnet that is magnetized
in one direction. Also, the magnetic circuit is constructed by the
flat horizontal coil, and the magnet. Therefore, the small and slim
structure can be provided. As a result, this audio equipment is
useful as the audio equipment such as the cellular phone, or the
like.
INDUSTRIAL APPLICABILITY
[0034] The audio equipment showing the high sound pressure
performance and having the small and slim structure can be
provided. This audio equipment is easy to manufacture at a low
cost.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 Views showing a structure of a magnetic circuit
according to a first embodiment of the present invention
respectively.
[0036] FIG. 2 Views showing a structure of a magnetic circuit
according to a second embodiment of the present invention
respectively.
[0037] FIG. 3 Views showing a structure of a magnetic circuit
according to a third embodiment of the present invention
respectively.
[0038] FIG. 4 Views showing a structure of a magnetic circuit
according to a fourth embodiment of the present invention
respectively.
[0039] FIG. 5 A sectional view of a slim speaker in the prior
art.
[0040] FIG. 6 A sectional view of another slim speaker in the prior
art.
[0041] FIG. 7 Perspective views of a magnet employed in the slim
speaker in the prior art.
[0042] FIG. 8 Views showing a state of a magnetic flux that is
formed by the magnet employed in the slim speaker in the prior
art.
[0043] FIG. 9 Views showing a structure of a magnetic circuit
according to a fifth embodiment of the present invention
respectively.
[0044] FIG. 10 Views showing a structure of a magnetic circuit
according to a sixth embodiment of the present invention
respectively.
[0045] FIG. 11 Views showing a structure of a magnetic circuit
according to a seventh embodiment of the present invention
respectively,
[0046] FIG. 12 Views showing a planar shape of a horizontal coil
respectively.
[0047] FIG. 13 Views showing a structure of an audio equipment
according to an eighth embodiment of the present invention
respectively.
DESCRIPTION OF REFERENCE NUMERALS
[0048] 3 magnet, 3a first polarity portion, 3b second polarity
portion, 4 horizontal coil, 5, 6, 7 ferromagnetic plate, 8 frame, 9
sound emitting hole, 10 cover, 11 diaphragm.
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